This is the equivalent of having your house searched because the government wants to see if you've committed any crimes. The 4th amendment expressly forbids it - without a warrant, or in the case of DUI - after officers have established probable cause (reckless driving, swerving, an accident, etc).
Additionally, anyone with 2 brain cells to rub together can figure out how to defeat an unsupervised breathalyzer test. You could have someone else blow into it, you could fill a balloon prior to drinking, someone like me could re-wire it to always blow negative.... It's foolish, like trusting a master lock - it's only there to keep honest people honest.
This system is also mandated to report data back to the government, a two-way communication that would, in theory, allow the government to remotely disable your vehicle.
In the cancel culture world, I can't see how this wouldn't be abused to punish political rivals..... "Ooh, he's a conservative with a plane ticket departing in an hour. Oops, your car won't start." or "A court date today? Nope, it's a bench warrant for you!" And when the system gets hacked (the government is running it), criminals can now affect the operation of first responder vehicles.
There's no way that a system like this isn't abused by everyone involved.
